<template>
    <div class="s-canvas">
      <canvas id="s-canvas" :width="contentWidth" :height="contentHeight"></canvas>
    </div>
  </template>
  <script>
  export default {
    name: "SIdentify",
    props: {
      identifyCode: {
        type: String,
        default: "1234"
      },
      fontSizeMin: {
        type: Number,
        default: 35
      },
      fontSizeMax: {
        type: Number,
        default: 35
      },
      backgroundColorMin: {
        type: Number,
        default: 180
      },
      backgroundColorMax: {
        type: Number,
        default: 240
      },
      colorMin: {
        type: Number,
        default: 50
      },
      colorMax: {
        type: Number,
        default: 160
      },
      lineColorMin: {
        type: Number,
        default: 100
      },
      lineColorMax: {
        type: Number,
        default: 200
      },
      dotColorMin: {
        type: Number,
        default: 0
      },
      dotColorMax: {
        type: Number,
        default: 255
      },
      contentWidth: {
        type: Number,
        default: 120
      },
      contentHeight: {
        default: 44
      }
    },
    methods: {
      // 生成一个随机数
      randomNum(min, max) {
        return Math.floor(Math.random() * (max - min) + min);
      },
      // 生成一个随机的颜色
      randomColor(min, max) {
        let r = this.randomNum(min, max);
        let g = this.randomNum(min, max);
        let b = this.randomNum(min, max);
        return "rgb(" + r + "," + g + "," + b + ")";
      },
      transparent() {
        return "rgb(255,255,255)";
      },
      drawPic() {
        let canvas = document.getElementById("s-canvas");
        let ctx = canvas.getContext("2d");
        ctx.textBaseline = "bottom";
        // 绘制背景
         ctx.fillStyle = this.randomColor(
           this.backgroundColorMin,
          this.backgroundColorMax
         );
        ctx.fillStyle = this.transparent();
        ctx.fillRect(0, 0, this.contentWidth, this.contentHeight);
        // 绘制文字
        for (let i = 0; i < this.identifyCode.length; i++) {
          this.drawText(ctx, this.identifyCode[i], i);
        }
     //绘制背景
         this.drawLine(ctx)
         this.drawDot(ctx)
      },
      drawText(ctx, txt, i) {
        ctx.fillStyle = this.randomColor(this.colorMin, this.colorMax);
        ctx.font =
          this.randomNum(this.fontSizeMin, this.fontSizeMax) + "px SimHei";
        let x = (i + 1) * (this.contentWidth / (this.identifyCode.length + 1));
        let y = this.randomNum(this.fontSizeMax, this.contentHeight - 5);
        var deg = this.randomNum(-10, 10);
        // 修改坐标原点和旋转角度
        ctx.translate(x, y);
        ctx.rotate((deg * Math.PI) / 180);
        ctx.fillText(txt, 0, 0);
        // 恢复坐标原点和旋转角度
        ctx.rotate((-deg * Math.PI) / 180);
        ctx.translate(-x, -y);
      },
      drawLine(ctx) {
        // 绘制干扰线
        for (let i = 0; i < 8; i++) {
          ctx.strokeStyle = this.randomColor(
            this.lineColorMin,
            this.lineColorMax
          );
          ctx.beginPath();
          ctx.moveTo(
            this.randomNum(0, this.contentWidth),
            this.randomNum(0, this.contentHeight)
          );
          ctx.lineTo(
            this.randomNum(0, this.contentWidth),
            this.randomNum(0, this.contentHeight)
          );
          ctx.stroke();
        }
      },
      drawDot(ctx) {
        // 绘制干扰点
        for (let i = 0; i < 100; i++) {
          ctx.fillStyle = this.randomColor(0, 255);
          ctx.beginPath();
          ctx.arc(
            this.randomNum(0, this.contentWidth),
            this.randomNum(0, this.contentHeight),
            1,
            0,
            2 * Math.PI
          );
          ctx.fill();
        }
      },
    },
    watch: {
      identifyCode(){
        this.drawPic();
      },

    },
    mounted() {
      this.drawPic();
      this.$nextTick(()=>{
        this.drawPic();
       
      })
      
    },
    }

  </script>

  <style  lang="less" scoped>
  @rootsize:37.5rem;
  div{
    height: (44 / @rootsize);
    box-sizing:border-box;
   
  }

  </style>
  